Cameron,
I recently became aware of Microsoft's involvement in the ECMAScript 3.1 effort as of about a month ago. (Including Allen & Pratap from MS Jscript, who are driving that effort.) ES3.1 makes a few subtle changes that I thought you'd like to follow up on, since they impact the WebIDL spec, namely "DontDelete" is changing to "Flexible", among other things which should be noted in WebIDL.
I've also done some recent investigation on how browsers handle ECMAScript's operators (delete, new, instanceof, etc.) and found that they are somewhat diverging in implementation; in particular the 'delete' operator. I've noted that some implementations use the delete operator in the DOM in the same spirit that it is speced in ECMAScript--that is the delete operator removes a given property completely. I've noted that other implementations only allow the delete operator to remove a "shadowed" property on the DOM, but never actual delete the underlying "built-in" property. I wondered if WebIDL makes any mention of the behavior of ECMAScript operators on host objects and how they should behave?
- Travis Leithead - OM Program Manager - Internet Explorer